It is known to protect working cabs or the cabs of motor vehicles against external influences with dust filters or also chemical absorption filters so that the occupants of the cabs are not troubled by the noxious substances present in the air brought in for ventilating purposes. The filters of this type are fabric filters or activated charcoal.
The known aeration and air removal system of the abovementioned type are disadvantageous in that, in a comparatively short time they are clogged by pollutants and in that the window areas of such cabs are easily covered by condensation.